Composite modified double base propellant with metal oxide stabilizer

ABSTRACT

Composite-modified double base propellants containing an oxide of a metal selected from the group consisting of cadmium, magnesium, aluminum, tin, lead, titanium, and zirconium. These metal oxides are compatible with ammonium perchlorate, act as a thermal stabilizer, and act as a gas inhibitor if a polyfunctional isocyanate is used as a cross linking agent.

atet 91 Berta 1 1 Sept. 16, 1975 COMPOSITE MODIFIED DOUBLE BASE 3,682,727 8/1972 Hcinzelmann et a1. 149/38 x PROPELLANT WITH METAL OXIDE 3,726,729 4/1973 Pierce 149/38 X 3.764.420 10/1973 Sayles 149/198 X STABILIZER 3.791.893 2/1974 Hill 149/198 X [75] Inventor: Dominic A, Berta, Wilmington, DeL 3,798,090 3/1974 Allabashi 149/19.4

[73] Assignee: The United States of America as represented by the Secretary of the Primary Examme'r-Bemamm R. Padgett Navy, Washington, Assistant ExaminerE. A. Miller [22] F] d M 23 1973 Attorney, Agehr, or FirmR. S. Sciascia; J. A. Cooke 1e ay [21] Appl. No.: 362,980 [57] ABSTRACT C0mpositemoclified double base propellants contain- [52] US. Cl. l49/19.4; 149/198, 149/20, ing an Oxideof a metal Selected from the group com 2 149/38 sisting of cadmium, magnesium, aluminum, tin, lead, [51] Int. Cl. C06D 5/06 titanium, and zirconium These metal Oxides are [58] Field of Search 149/19.4, 19.8, 38, 20 patible with ammonium perchlorate, act as a thermal [56] R f Cted stabilizer, and act as a gas inhibitor if a polyfunctional e erences l isocyanate is used as a cross linking agent.

26 Claims, N0 Drawings COMPOSITE MODIFIED DOUBLE BASE PROPELLANT WITH METAL OXIDE STABILIZER BACKGROUND OF THE INVENTION This invention relates generally to high thrust composite modified double base propellants and more particularly to thermal stabilizers for composite-modified double base (CMDB) propellants.

The standard composite-modified double base (CMDB) propellants contain nitroglycerin and nitrocellulose. In these propellants highest performance is achieved by minimizing the amount of nitrocellulose. However, the nitrocellulose then has to be crosslinked with polyfunctional isocyanates in order to achieve mechanical properties suitable for case-bonded applications.

An oxidizer is also used in CMDB propellants to in crease the oxidation index high enough to assure efficient performance or to achieve a desired burning rate. The oxidizer most often used is ammonium perchlorate. In addition, a thermal stabilizer is also usually re quired and the stabilizer which is the most compatible with ammonium perchlorate is resorcinol.

Thus, CMDB propellants often contain both resorcinol and polyfunctional isocyanates but the presence of resorcinol with an isocyanate causes serious processing problems because of the reaction between these two propellant ingredients. This reaction competes with the reaction of the polyfunctional isocyanate and nitrocellulose and thus decrease the degree of crosslinking which can be obtained with a given amount of nitrocel lulose. Further the reaction between resorcinol and the polyfunctional isocyanate generates carbon dioxide. This gas causes serious porosity problems. A particularly attractive solution to the problem would be to replace resorcinol with a stabilizer which would not react with isocyanates. However, the heretofore known stabilizers could not be used as satisfactory substitutes for resorcinol because of their incompatibility with ammonium perchlorate.

SUMMARY OF THE INVENTION Accordingly, one object of this invention is to provide a CMDB rocket propellant.

Another object of this invention is to decrease the porosity of CMDB propellants containing ammonium perchlorate and isocyanates.

Yet another object of this invention is to improve the crosslinking of isocyanates with nitrocellulose in CMDB propellants.

A still further object of this invention is tov enhance the thermal stability of CMDB propellants containing isocyanates.

. Yet another object of this invention is to provide an alternative to resorcinol for thermally stabilizing compositemodified double base propellants.

These and other objects are attained by the substitu tion of an oxide of a metal selected from the group consisting of cadmium, magnesium, aluminum, tin, lead, titanium, and zirconium for resorcinol in CMDB pro pellants.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The thermal stabilizer of this invention can be used in any CMDB propellant system in which resorcinol can be used. However the best use of these stabilizers occur in propellants containing a polyfunctional isocyanate. In those propellants the thermal stabilizers of this invention avoid the reaction of the polyisocyanate with the hydroxyl groups of resorcinol. Thus the degree of crosslinking is improved and the porosity problems caused by the resulting gas evolution are avoided.

The CMDB propellants encompassed by this invention contain a number of art recognized ingredients. Some of the possible choices are now listed along with their amounts given in weight percentages of the total propellant composition.

For example the binder may consist of nitrocellulose or plastisol nitrocellulose in an amount of 1-15 weight percent of the total propellant composition.

Any of the art recognized plasticizers can be used in the instant. composition. Typical plasticizers would be nitroglycerin, dioetyladipate, triacetin or mixtures thereof with a mixture of nitroglycerin and triacetin being the most preferred. The plasticizer should preferably constitute l5-60 weight percent of the total propellant composition.

Any of the art recognized oxidizers can also be used in the instant composition such as, for example, perchlorates, nitrates, eyclotetramethylenetetranitramine cyclotrimethylenetrinitramine or mixtures thereof with ammonium perchlorate being the most preferred. This constituent should comprise 5 to 50 weight percent of the total propellant composition.

Any of the art recognized metal fuels can also be utilized and should constitute 325 weight percent of the propellant composition. Typical metal fuels include aluminum, zirconium, lithium, magnesium, or a mixture thereof with aluminum being most preferred.

Of the polyfunctional isocyanate crosslinking agents, toluene and hexamethylene are the most preferred. The amount of the isocyanate should be about 0.l4 weight percent of the total composition.

As is well known in the art, other ingredients may also be added to alter the ballistics or the mechanical properties e.g. combustion catalysts or stabilizers.

The new stabilizer of this invention is an oxide of a metal selected from the group consisting of cadmium, magnesium, aluminum, tin, lead, titanium, zirconium and mixtures thereof and it should constitute about 0.5 to 5 weight percent of the total propellant composition with l2 weight percent being most preferred.

The general nature of the invention having been set forth, the following examples are present as specific illustrations thereof.

, EXAMPLE 1 nitroglycerin 26.00 triacetin 4.68 plastisol nitrocellulose 4.00 ammonium perchlorate 49.00 aluminum l4.00 ,Z-nitrodiphenylamine 1.00 toluene diisocyanate 0.32 cadmium oxide 1.00

EXMPLE II nitroglycerin 26.00 triacetin 4.68 plastisol hitroeellulosc 4.00 ammonium pelehlorate 49.00 aluminum l4.00 z-nirmdiphenylamihe 1 .00

I -Continued toluene diisocyanate 0.32 cadmium oxide 200 EXAMPLE lll nitroglycerin 1 26.00 triacetin 4.68 plastisol nitrocellulose 4.00 ammonium perchlorate 49.00 aluminum l4.()() Z-nitrodiphenylamine 1.00 toluene diisocyanate 0.32 magnesium oxide I.()()

'The use of the stabilizers of this invention does not present any additional processing problems. In fact they facilitate the preparation of crosslinked CMDB propellants becauseof the elimination of the gassing problem caused by the reaction between resorcinol and the polyfunctional isocyanate. Hence any standard method of preparation may be used with this invention.

Obviously, numerous modifications and variations of the present invention are possible in light of the above teachings. It is therefore understood that within the scope ofthe appended claims the invention may be practiced otherwise than as specifically described herein. 7 V

What is claimed as new and desired to be secured by Letters Patent of the United States is: i

l. A resorcinol -free composite-modified double base propellant consisting essentially of 1 an oxidizer, (2) ametal fuel, (3 a polyfunctional isocyanate, (4) a plasticizer, (5) a binder selected from the group consisting of nitrocellulose and plastisol nitrocellulose, (6) an oxide of a metal selectedfrom the group consisting of cadmium, magnesium, aluminum, tin, lead. titanium, zirconium and mixtures thereof as the stabilizer.

2. The propellant of claim I wherein said oxidizer constitutes about 5-50 weight percent, said metal fuel constitutes about 3-25 weight percent, said polyfunctional isocyanate constitutes about 0.l4 weight percent, said plasticizer constitutes about -6Q weight percent, said binder constitutes about l-l 5 weight per cent and said oxide constitutes about 0.5-5 weight percent of said composition.

3. The propellant of claim 2 wherein said oxidizer is selected from the group consisting of perehlorates, nitrates, cyclotetramethylenctetranitramine.

4. The propellant of claim 2 wherein said oxidizer is ammonium perchlorate.

5. The propellant of claim 2 wherein said metal fuel is selected from the group consisting of aluminum, zirconium, lithium, magnesium and mixtures thereof.

6. The propellant of claim 2 wherein said polyfunctional isocyanate is selected from the group consisting of toluene diisocyanate, hexamcthylene diisocyanatc and mixtures thereof.

7. The propellant of claim 2 wherein said plasticizer is selected from the group consisting of nitroglycerin. dioctyladipate. triacctin, and mixtures thereof.

8. The propellant of claim 2 wherein the metal oxide constitutes about l-2 weight percent of the total propellant composition.

9. The propellant of claim 2 wherein said oxide is cadmium oxide.

10. The propellant of claim 8 wherein said oxide is cadmium oxide.

11. A method of thermally stabilizing a resorcinolfree compositemodified double base propellant comprising adding an oxide of a metal selected from the group consisting of cadmium, magnesium, aluminum, tin, lead, titanium, zirconium and mixtures thereof as the stabilizer to said propellant. 7

12. The method of claim 11 wherein about 0.5 to 5 weight percent of the metal oxide is added to the propellant.

13. A method of thermally stabilizing a resorcinolfree composite-modified double base propellant having ammonium perchlorate as an oxidizer and having nitrocellulose crosslinked with an isocyanate comprising adding an oxide selected from the group consisting of cadmium, magnesium, aluminum, tin, lead, titanium, zirconium and mixtures thereof as the stabilizer to the propellant. i

14. The method of claim 13 wherein about 0.5 to 5 weight percent of said metal oxide is added to the propellant. k

15. A method of decreasing porosity in resorcinolfree composite-modified double base propellants having an isocyanate as a crosslinking agent comprising adding an oxide ofa metal selected from the group consisting of cadmium, magnesium, aluminum, tin, lead, titanium, zirconium and mixtures thereof as the stabilizer to the propellant.

16. The method of claim 15 wherein about 0.5-5 weight percent of the metal oxide is added to the propellant.

17. A resorcinol-free composite-modified double base propellant consisting essentially of( l an oxidizer, (2) a metal fuel, (3) a poly-functional isocyanate, (4) a plasticizer, (5) a binder selected from-the group consisting of nitrocellulose and plastisol nitrocellulose, and (6) an oxide of a metal selected from the group consisting of cadmium, and magnesium and mixtures thereof as the stabilizer.

l8. The propellant of claim 17 wherein said oxidizer constitutes about 5-50 weight percent, said metal fuel constitutes about 3-25 weight percent. said polyfunctional isocyanate constitutes about 0.1-4 weight percent, said plasticizer constitutes about 15-60 weight percent, said binder constitutes about l-l 5 weight percent and said oxide constitutes about 0.5-5 weight percent of said composition.

19. The propellant of'claim 18 wherein said oxidizer is selected from the group consisting of perchlorates. nitrates, and cyclotetraniethylenetetranitramine.

20. The propellant of claim 18 wherein said oxidizer is ammonium perchlorate.

21. The propellant of claim 18 wherein said metal fuel is selected from the group consisting of aluminum, zirconium, lithium. magnesium and mixtures thereof.

22. The propellant of claim 18 wherein said poly functional isocyanate is selected from the group consisting of toluene diisocyanate, hexamcthylene diisocyanate and mixtures thereof.

23. The propellant of claim 18 wherein said plasticizer isselected from the group consisting of nitroglycerin, dioctyladipate. triacetin, and mixtures thereof.

24. The propellant of claim 18 wherein the metal oxide constitutes about [-2 weight percent of the total propellant composition.

25. The propellant of claim 18 wherein said oxide is cadmium oxide.

26. The propellant of claim 24 wherein said oxide is cadmium oxide. 

1. A RESORCINOL-FREE COMPOSITE-MODIFIED DOUBLE BASE PROPELLANT CONSISTING ESSENTIALLY OF (1) AN OXIDIZER, (2) A METAL FUEL, (3) A POLYFUNCTIONAL ISOCYANATE, (4) A PLASTICZER, (5) A BINDER SELECTED FROM THE GROUP CONSISTING OF NITROCELLULOSE AND PLASTISOL NITROCELLULOSE, (6) AN OXIDE OF A METAL SELECTED FROM THE GROUP CONSISTING OF CADMIUM MANGNESIUM, ALUMINUM, TIN, LEAD, TITANIUM, ZIRCONIUM AND MIXTURES THEREOF AS THE STABILIZER.
 2. The propellant of claim 1 wherein said oxidizer constitutes about 5-50 weight percent, said metal fuel constitutes about 3-25 weight percent, said polyfunctional isocyanate constitutes about 0.1-4 weight percent, said plasticizer constitutes about 15-60 weight percent, said binder constitutes about 1-15 weight percent and said oxide constitutes about 0.5-5 weight percent of said composition.
 3. The propellant of claim 2 wherein said oxidizer is selected from the group consisting of perchlorates, nitrates, cyclotetramethylenetetranitramine.
 4. The propellant of claim 2 wherein said oxidizer is ammonium perchlorate.
 5. The propellant of claim 2 wherein said metal fuel is selected from the group consisting of aluminum, zirconium, lithium, magnesium and mixtures thereof.
 6. The propellant of claim 2 wherein said polyfunctional isocyanate is selected from the group consisting of toluene diisocyanate, hexamethylene diisocyanate and mixtures thereof.
 7. The propellant of claim 2 wherein said plasticizer is selected from the group consisting of nitroglycerin, dioctyladipate, triacetin, and mixtures thereof.
 8. The propellant of claim 2 wherein the metal oxide constitutes about 1-2 weight percent of the total propellant composition.
 9. The propellant of claim 2 wherein said oxide is cadmium oxide.
 10. The propellant of claim 8 wherein said oxide is cadmium oxide.
 11. A method of thermally stabilizing a resorcinol-free composite-modified double base propellant comprising adding an oxide of a metal selected from the group consisting of cadmium, magnesium, aluminum, tin, lead, titanium, zirconium and mixtures thereof as the stabilizer to said propellant.
 12. The method of claim 11 wherein about 0.5 to 5 weight percent of the metal oxide is added to the propellant.
 13. A method of thermally stabilizing a resorcinol-free composite-modified double base propellant having ammonium perchlorate as an oxidizer and having nitrocellulose crosslinked with an isocyanate comprising adding an oxide selected from the group consisting of cadmium, magnesium, aluminum, tin, lead, titanium, zirconium and mixtures thereof as the stabilizer to the propellant.
 14. The method of claim 13 wherein about 0.5 to 5 weight percent of said metal oxide is added to the propellant.
 15. A method of decreasing porosity in resorcinol-free composite-modified double base propellants having an isocyanate as a crosslinking agent comprising adding an oxide of a metal selected from the group consisting of cadmium, magnesium, aluminum, tin, lead, titanium, zirconium and mixtures thereof as the stabilizer to the propellant.
 16. The method of claim 15 wherein about 0.5-5 weight percent of the metal oxide is added to the propellant.
 17. A resorcinol-free composite-modified double base propellant consisting essentially of (1) an oxidizer, (2) a metal fuel, (3) a poly-functional isocyanate, (4) a plasticizer, (5) a binder selected from the group consisting of nitrocellulose and plastisol nitrocellulose, and (6) an oxide of a metal selected from the group consisting of cadmium, and magnesium and mixtures thereof as the stabilizer.
 18. The propellant of claim 17 wherein said oxidizer constitutes about 5-50 weight percent, said metaL fuel constitutes about 3-25 weight percent, said polyfunctional isocyanate constitutes about 0.1-4 weight percent, said plasticizer constitutes about 15-60 weight percent, said binder constitutes about 1-15 weight percent and said oxide constitutes about 0.5-5 weight percent of said composition.
 19. The propellant of claim 18 wherein said oxidizer is selected from the group consisting of perchlorates, nitrates, and cyclotetramethylenetetranitramine.
 20. The propellant of claim 18 wherein said oxidizer is ammonium perchlorate.
 21. The propellant of claim 18 wherein said metal fuel is selected from the group consisting of aluminum, zirconium, lithium, magnesium and mixtures thereof.
 22. The propellant of claim 18 wherein said polyfunctional isocyanate is selected from the group consisting of toluene diisocyanate, hexamethylene diisocyanate and mixtures thereof.
 23. The propellant of claim 18 wherein said plasticizer is selected from the group consisting of nitroglycerin, dioctyladipate, triacetin, and mixtures thereof.
 24. The propellant of claim 18 wherein the metal oxide constitutes about 1-2 weight percent of the total propellant composition.
 25. The propellant of claim 18 wherein said oxide is cadmium oxide.
 26. The propellant of claim 24 wherein said oxide is cadmium oxide. 